A gate driver circuit is a specialized circuit that accepts a low-power input and produces a high-current drive input for the gate of a high-power transistor such as a power metal-oxide-semiconductorfield-effect transistor (MOSFET). Gate drivers can be provided either on-chip or as a discrete module.
In order to protect the external transistor from overheating in the event of a short circuit between the transistor's drain and its power supply, certain gate driver integrated circuits monitor the drain voltage and compare it to a reference voltage that is representative of a short circuit condition. If the drain-source voltage exceeds the reference voltage when the transistor is turned on, the gate driver circuit pulls the gate-source voltage low in order to turn off the transistor and limit damage caused by excessive heat generation. However, during normal switching on of the external transistor, the drain-source voltage takes a certain period of time to decay to a level that is less than the reference voltage due to the slew rate of the drain voltage. Thus, certain gate driver integrated circuits employ a blanking timer that, for a predetermined fixed amount of time following the switching on of the transistor, prevents the short circuit detection circuitry from causing the transistor to be turned off. Such a blanking timer needs to implement a fixed blanking time that is both long enough to cover normal switch-on slewing time, and short enough to prevent excessive heat generation in the event of an actual drain-to-power-supply short circuit from damaging the device. In some cases it is not possible to satisfy both of these requirements.